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排序方式: 共有196条查询结果,搜索用时 15 毫秒
61.
62.
Odile Thiéry Mari Moora Martti Vasar Martin Zobel Maarja Öpik 《Symbiosis (Philadelphia, Pa.)》2012,58(1-3):135-147
Most molecular ecological studies of arbuscular mycorrhizal fungi (AMF) have been based on the rRNA gene sequences. However, information about intraspecific nucleotide variation is still limited in these fungi. In this study, we calculated the inter- and intrasporal nucleotide variation of Diversispora sp. EE1 using 78 cloned sequences from four spores within a ca 4960 bp fragment of the nuclear ribosomal operon spanning the near full length small ribosomal subunit (SSU) rRNA gene, the full internal transcribed spacer (ITS: ITS1-5.8S-ITS2) and ca 2740 bp of the large ribosomal subunit (LSU) rRNA gene. Data for each marker region (SSU, ITS and LSU) originated from the very same spores. Sequence variation resulting from point mutations and small indels was recorded in all regions. Highest sequence variation was observed in the ITS region at both the inter- and intrasporal levels. The ITS1 component was more variable than ITS2, whilst the 5.8S gene was the least variable component of the ITS region. Evolutionary divergence of gene copies between spores was intermediate for the LSU and lowest for the SSU. The SSU and the LSU genes had relatively similar evolutionary divergence per spore. Sequence variant richness was not exhaustive for any of the marker regions, indicating that multiple sequences per spore from multiple spores are needed when characterizing a species. This study provides reference sequences for ecological studies, permitting identification of AMF using any of the ribosomal regions or primer systems. 相似文献
63.
Plant traits determine the phylogenetic structure of arbuscular mycorrhizal fungal communities 总被引:1,自引:0,他引:1
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Álvaro López‐García Sara Varela‐Cervero Martti Vasar Maarja Öpik José M. Barea Concepción Azcón‐Aguilar 《Molecular ecology》2017,26(24):6948-6959
Functional diversity in ecosystems has traditionally been studied using aboveground plant traits. Despite the known effect of plant traits on the microbial community composition, their effects on the microbial functional diversity are only starting to be assessed. In this study, the phylogenetic structure of arbuscular mycorrhizal (AM) fungal communities associated with plant species differing in life cycle and growth form, that is, plant life forms, was determined to unravel the effect of plant traits on the functional diversity of this fungal group. The results of the 454 pyrosequencing showed that the AM fungal community composition differed across plant life forms and this effect was dependent on the soil collection date. Plants with ruderal characteristics tended to associate with phylogenetically clustered AM fungal communities. By contrast, plants with resource‐conservative traits associated with phylogenetically overdispersed AM fungal communities. Additionally, the soil collected in different seasons yielded AM fungal communities with different phylogenetic dispersion. In summary, we found that the phylogenetic structure, and hence the functional diversity, of AM fungal communities is dependent on plant traits. This finding adds value to the use of plant traits for the evaluation of belowground ecosystem diversity, functions and processes. 相似文献
64.
Genome Scan for Predisposing Loci for Distal Interphalangeal Joint Osteoarthritis: Evidence for a Locus on 2q 总被引:12,自引:0,他引:12
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Jenni Lepp?vuori Urho Kujala Jaakko Kinnunen Jaakko Kaprio Martti Nissil? Markku Heli?vaara Nina Klinger Jukka Partanen Joseph D. Terwilliger Leena Peltonen 《American journal of human genetics》1999,65(4):1060-1067
The genetic contribution to common forms of osteoarthritis (OA) is well established but poorly understood. We performed a genome scan, using 302 markers for loci predisposing to distal interphalangeal joint (DIP) OA. To minimize genetic heterogeneity in our study sample, we identified siblings with a severe, radiologically defined phenotype from the nationwide registers of Finland. In the initial genome scan, linkage analysis in 27 sibships gave a pairwise LOD score (Z) >1.00 with nine of the screening markers. In the second stage, additional markers and family members were genotyped in these chromosomal regions. On 2q12-q13, IL1R1 resulted in Z=2.34 at recombination fraction (theta) 0, allowing a dominant mode of inheritance. Association analysis of markers D2S2264, IL1R1, D2S373, and D2S1789 jointly provided some evidence for a shared haplotype among the affected individuals (P value of.012). Also, multipoint nonparametric linkage analysis yielded a P value of.0001 near the locus IL1R1 and P=.0007 approximately 20 cM telomeric near marker D2S1399, which, in two-point analysis, gave Z=1.48 (straight theta=. 02). This chromosomal region on 2q harbors the interleukin 1 gene cluster and, thus, represents a good candidate region for inflammatory and autoimmune disorders. Three additional chromosomal regions-4q26-q27, 7p15-p21, and Xcen-also provided some evidence for linkage, and further analyses would be justified to clarify their potential involvement in the genetic predisposition to DIP OA. 相似文献
65.
Finishing, i.e. gap closure and editing, is the most time-consuming part of genome sequencing. Repeated sequences together with sequencing errors complicate the assembly and often result in misassemblies that are difficult to correct. Repeat Discrepancy Tagger (ReDiT) is a tool designed to aid in the finishing step. This software processes assembly results produced by any fragment assembly program that outputs ace files. The input sequences are analyzed to determine possible differences between repeated sequences. The output is written as tags in an ace file that can be viewed by, e.g. the Consed sequence editor. AVAILABILITY: The ReDiT program is freely available at http://web.cgb.ki.se/redit 相似文献
66.
The activity levels of DNA polymerases α and β have been measured by autoradiography in squash preparations from rat testis of sexually mature animals. Similar results were obtained with ‘fixed’ samples (dipped in acetone: ethanol for 5 min at 25 °C) or ‘unfixed’ samples (frozen in liquid nitrogen and freeze-dried). The activities of DNA polymerases α and β in situ were distinguished by differential assay conditions and by selective inhibition with compounds such as N-ethylmaleimide and aphidicolin. Using the endogenous chromatin as template, maximal activity for both enzymes was obtained in the presence of all four deoxyribonucleoside triphosphates, MgCl2 and ethylene glycol. When DNA polymerase activities in several predominant testicular cell types (pre-leptotene primary spermatocytes, pachytene primary spermatocytes, round spermatids and elongated spermatids) were quantitatively compared, on a per cell basis, the following percentage distribution was observed:
Pre-leptotene primary spermatocyte % | Pachytene primary spermatocyte % | Round spermatid % | Elongated spermatid % | |
DNA polymerase α | 25 | 42 | 30 | 3 |
DNA polymerase β | 29 | 34 | 36 | 1 |